The present invention relates to a daisy-wheel type printer, and more particularly to a type thereof in which erasure operation is made by pressing a correction ribbon several times with a print hammer.
In a conventional printer of this type, a print image can be formed by striking a type of tile daisy wheel from behind by a print hammer driven by a solenoid. For erasing the print image thus formed, Japanese Patent Application Kokai No. 58-142883 discloses an erasing method in which the print hammer repeatedly strikes the printed character through the type and a correction ribbon. The first strike of the hammer is weak enough so that ink does not permeate into the printing paper. Then the next strike is stronger than the first. With this erasing method, printed character can be almost perfectly erased.
In a commonly assigned U. S. patent application Ser. No. 07/813,493 filed on Dec. 26, 1991, disclosed is a printer having a print hammer driven in association with a cam body rotated by a motor. The printing hammer presses the rear side of the type, so that the type is depressed onto the printing paper through the printing ribbon to thus perform printing.
Accordingly, the latter printer where the type is pressed can reduce noise generated during printing in comparison with the former printer where the rear side of the type is struck by the print hammer.
However, in the latter pressor type printer, the type and the printing paper are in contact from several mS to several ten mS. This is longer than the several hundred .mu.S to several mS range of the former impact type printer.
If the method wherein characters are erased by striking them several times is applied to the pressor type printer in which prolonged contacting period results between the type and the printing sheet, ink transferred to the correction ribbon at the initial pressing operation for erasing is retransferred onto the printing sheet in the second and subsequent erasure operation or alternatively, adhesive material on the correction ribbon may be transferred to the printing sheet. As a result, complete character erasing may not be achievable, and printing quality may be extremely degraded if the printing is achieved on a character-erased portion provided by the adhesive material.